mmc: jz4740: remove unused struct component card_detect_irq

I have not found any user for this struct component.
Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>
Reviewed-by: Paul Cercueil <paul@crapouillou.net>
Link: https://lore.kernel.org/r/415ea1cb85eedc12f0c2f70da9a1ae3885bdd091.1608714110.git.hns@goldelico.comSigned-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/jz4740_mmc.c

@@ -152,7 +152,6 @@ struct jz4740_mmc_host {
 	enum jz4740_mmc_version version;
 
 	int irq;
-	int card_detect_irq;
 
 	void __iomem *base;
 	struct resource *mem_res;